Tracing the “great, great grandmothers” of the chicken world

Dr Alice Storey, an archaeologist at the University of New England, is tracing the global migration routes of domestic chickens back through thousands of years towards their origins in the jungles of South-east Asia.

In doing so, Dr Storey is pioneering the use of DNA from ancient chicken bones recovered from well-dated archaeological sites around the world. This is enabling her to add a fourth dimension – that of time – to an emerging “map” of chicken dispersal. One of the ultimate goals of such research is identifying the original Asian centres of jungle fowl domestication.

“All of our domestic chickens are descended from a few hens that I like to think of as the ‘great, great grandmothers’ of the chicken world,” Dr Storey said.

Biological, linguistic, historical and archaeological data have all contributed to an understanding that chickens accompanied human movements from their Asian homeland west through the Middle East to Europe and Africa, and east through the islands of South-east Asia and the Pacific.

Dr Storey’s analysis of ancient DNA is disentangling complications in this broad picture caused by interactions later than the original dispersal. “Only ancient DNA provides a unit of analysis with the chronological control necessary to reconstruct and disentangle the signals of initial dispersals from those of later interactions,” she said. Hers are the first published reports on the use of ancient DNA in this context.

A paper by Dr Storey and her colleagues, titled “Global dispersal of chickens in prehistory using ancient mitochondrial DNA signatures”, is published today in the online scientific journal PLoS ONE.

The paper provides evidence for dispersal out of Asia over 3,000 years ago involving the movement of chickens both westwards to Europe and eastwards into the Pacific.

One of the most striking results of the study was the discovery of the same DNA signature in ancient chicken bones from Europe, Thailand, the Pacific and Chile, and from Spanish colonial sites in Florida and the Dominican Republic. This means that chickens dispersed both westwards and eastwards from a single ancient domestication centre, and converged thousands of years later when the Spanish brought their chickens from Europe to the New World.

“While unambiguous data does not yet exist to trace any of the detected mitochondrial DNA signatures back to specific domestication centres, the analysis of ancient DNA sequences presented here is an important first step towards it,” the paper concludes.